Electrical socket and plug systems are common in portable electronic devices that need to be charged by electricity. However, the opening of the socket, to which the plug is typically inserted is susceptible to contamination, moisture and other harmful effects that may hinder the operation of the plug-socket system. Therefore it is important to protect the socket-plug systems by providing a seal to protect the socket and the plug from the aforementioned disadvantages.
Document U.S. Pat. No. 4,948,377 by Cairns presents a bladder that can be used to protect an electric device when submersed in water. This document is cited here as reference. In U.S. Pat. No. 4,948,377 a seal is provided for the socket-plug system to protect it from high pressure salt water. These seals in accordance with the prior art are annular and elastic in structure, and protect against the symmetric hydrostatic pressure of the salt water.
I.e. symmetric pressure means a pressure which is even on the surface to which it is applied. The annularity of the seal has the clear disadvantage that if the seal is subjected to asymmetric pressure, the seal will be compressed harder where the pressure is the hardest, but will be looser in the places where the pressure is less. This effect can be experimented with a rubber circle, if it is pressed from two sides, it will tend to take an oval shape by compressing from the sides it is pressed, and bulging from the sides it is not pressed from. I.e. asymmetric pressure means a pressure which is uneven at some points of the surface to which it is applied.